Many electronic devices, such as cell phones, smart watches, tablet computers, and personal digital assistants, have input surfaces or displays through which a user may interact with the electronic device by applying a press or touch force. The location and/or strength of the touch on the input surface can be related to the action to be performed by the electronic device. Some known sensor mechanisms for detecting the location and strength of the touch on the input surface may use technologies based on capacitance changes or on piezoelectric or piezoresistive changes in sensors placed near the input surface.
Other sensor mechanisms may involve light-based measurements. An emitted light, such as laser light, may be reflected, scattered, or otherwise altered, with the alteration related to the distance from the cause of the alteration. In some embodiments, a reflection of a laser light emitted from a laser diode can be detected either by a photodetector or by undergoing self-mixing interference with the laser itself. In the case of a display surface, a touch by a user on the input surface can cause a deflection of the input surface or may modify the reflection properties of the light from the input surface. The deflection or modification can cause an alteration in a laser light directed toward the input surface. Such light-based sensor mechanisms may offer sensitive and reliable detection of a touch, scroll, or applied force on an input surface.
Examples of such light-based sensors may include LIDAR systems. Such light-based sensor mechanisms may be configured to measure distance or displacement of just a single location on a target object. In the case of a user input surface, detecting a user input at a large number of locations across the user input surface would require a corresponding number of light-based sensor mechanisms that each detect distance or displacement from a respective single location on a target object. Various embodiments disclosed herein are directed to light-based sensor mechanisms that may measure distance, displacement, or speed of movement at multiple locations on a target object using a single laser light source.